With the rapid technological advances, many of the computer information industry, communication and consumer electronic products are changing very fast. Looking at the entire electronics industry, the development features are:
1. Increasingly high application frequency,
2. Higher and higher manufacturing technology level.
As for printed circuit boards, the direction of development is becoming low dielectric, low thermal expansion, multi-layer, high thermal resistance and so on, meanwhile complying with environment-friendly requirements; electronics and communication products also tend to be light, thin, short and to meet high-reliability, multi-function and environmental protection requirements. Since the high-frequency technology is being used in the wireless networks and communication equipments, the demand for high-frequency substrates is bound to become the future trend of development. In short, high-frequency communication substrate materials used require nothing more than to send data quickly and not to cause data loss or interference in the process of transmission; therefore, high-frequency communication equipments selected in production must have the following basic features:
(1) Small and stable dielectric constant,
(2) Low dissipation factor,
(3) Low water absorption,
(4) Good chemical resistance,
(5) Good thermal resistance.
The electrical characteristics of the printed circuit board material depend on the three main composite material types of the substrate: (i) resin, (ii) filler, and (iii) reinforcement materials. As for the resin system, the current used FR-4 (Tg140° C.) substrate made from the combination of epoxy resin (such as Nan Ya's NPEB454A80) and glass fiber (E glass) shows a “dielectric constant” (abbreviated as Dk) value of 4.6 only, which can not meet the requirements in the field of the high frequency transmission. Different resin systems (such as “bismaleimide triazine” resin (abbreviated as BT), cyanate ester resin, PTFE resins (Polytetrafluoroethylene) and so on are gradually developed, but the new developed resin system shows big deviations from the current substrate manufacturing and processing conditions, and can not be used in the existing equipments, thus it can not be widely applied.